Gaining an understanding of the mechanisms by which cells process and respond to extracellular cues has become a major goal in many areas of bi- ogy and has attracted the attentions of almost every traditional discipline within the biological sciences. At the heart of these divergent endeavors are common methods that can aid biochemists, physiologists, and pharmacologists in ta- ling the specific questions addressed by their research. In Receptor Signal Transduction Protocols, a diverse array of meth- ologies employed to interrogate ligand--receptor and receptor-effector int- actions are...